Hrmm. Why do you think two layers of translation would be needed?
I tried what you suggested but it didn't work. It also seems like your suggestion would've needed to be calling the functions on a 3dCamera object, not with the system functions. Right? I tried that too but it also didn't work.
Honestly I feel like the most logical way to do this would just be to use these for the x and the y coordinates of the tile I'm trying to create:
For x:
3DCamera.CanvasToLayerX("3dLayer", Touch.X, Touch.Y, 0)
For y:
3DCamera.CanvasToLayerY("3dLayer", Touch.X, Touch.Y, 0)
But unfortunately this doesn't work. If you have more suggestions I'm all ears. Or Ashley might know?